Which boat are you building?

Sorry I am building a Shearwater Sport Hybird

Not sure exactly what you're describing as the problem.  I just tried to get the forms at close to the 1 ft interval, and perpendicular to the long axis of the boat.  The notches didn't fit all that close, but it came out fine, and there is a big swoop in the boat in front of the cockpit.  the most important thing is to have a smooth arc from the forms to the shear (cross-section view).

Maybe these pics will help.  You got pics of your issue?

When I did my SW Sort Hybrid, I had a similiar concern.  My decision was just a series of "tweaks" to get the deck shape fair.  Your eye will tell you when it looks good.  I used some shims here and there to create a nice shape, using hot glue to hold them in place.  You can lay a couple of strips down with small clamps, or staples to use as battens to see what the finished shape will be. At that point you can do more fine tuning.

While we're on this topic, can anyone comment on how to temporarily keep forms in place while checking their alignment?  My experience so far is that  the hot glue holds the forms too well to allow for multiple adjustments.  Also its a bit messy to cleanup from the inside of the hull.  I'm doing a wood duck hybrid....

I found it easy to hold the deck forms in place while making the small adjustments in their position, by placing a shim between the hull and their sides.  The shims come in packs of 2 dozen at the hardware store for cheap.

They wedge in real well near the bottom of the forms, and once you get the form where you like it, just hot glue the form in place without moving the shims.  I tried to not get too much glue on the shims, but didn't worry about it much, and at the end it was no problem using a soft mallet to dislodge the forms.

Thanks Hickory, I figured out my mistakes for your pictures. I had to make a new form to replace the one I royally screwed up. I was way over analyzing the directions. Back on track now, just wish the weather would cooperate. 

We have been wringing our hands over deck forms for hybrid kayaks for years.  We model the decks in the computer, cut the parts and...they don't fit perfectly.

The culprit is the sheer clamp.  Every single kayak fitted with a sheer clamp will exhibit a tiny bit of variation in the plan view, because every pair of sheer clamps is going to bend a little bit differently.  This is all above the waterline, so it doesn't harm the boat, and it's not even visible.  But often the temporary forms are loose in the boat, or too tight.

(ShopCam watchers will note that we are building an entire Mill Creek 16.5 and an entire Mill Creek 13 to check the fit of the deck forms for the hybrid option.)

We're edging closer to Ikea-like fits in the newer generation plywood kits.  But strip-planking ANYTHING is going to require some cutting and fitting.  It's okay to slide the forms around slightly to fit better, or to whittle on the notches if they are too tight.  

Some of our hybrid kayaks don't have sheer clamps (the Night Herons and Wood Ducks) and we get a lot fewer calls about those forms.  BUT, deck installation in those boats is a messier operation, and it complicates the installation of bulkheads.

John

Well glad to hear that I am not the only one how has run into issues. I got the deck forms all algined and true. just took some patience and a lot of counting to ten.

I am having the same issues with the Shearwater sport hybrid forms. For some reason the hull is wider (didn't snap back) at almost all the form locations.

the notches in the forms are often deeper than shear clamp piece so the forms are proud even before planning the shear clamp.  I have experimented with pulling the sides in with a clamp until the forms are held in place but I don't like the idea of already stresssing the structure.

What is the best reference point for the forms?
The bottom of the notches against the bottom of the shear clamp?
The sides of the forms against the hull( at what height)?

MY inclination is to use shims to position the form as best as possible  to miantain the form slope to the top of the side panel ( it seams that the it should get a hair steeper)  but I worry that this might result in an undualting  line.

Suggestions, references appreciated. 

Pablo deTorres

If you look at Hickory's photo, I think you will see the curvature of the deck should be fair to the shear clamp.  The deck, when completed, should be touching at the outside edge so it is tight to the hull.  I would have the forms at the correct location, fore and aft, then move them up and down until the line of the top of the mold blends right into the top of the hull (shear clamp).Lay a thin strip of wood, a batten,tight, along the top of the mold and see how it lands on the shear clamp, that would be one way to reference it. After you get them where you thing they look good, lay a couple of strips in several locations, along the length of the deck, to help you envision what the final shape will be.